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Briana L. Gross, Gayle M. Volk, Christopher M. Richards, Patrick A. Reeves, Adam D. Henk, Philip L. Forsline, Amy Szewc-McFadden, Gennaro Fazio, and C. Thomas Chao

Large field collections of plant genetic resources, although critical for many clonal and perennial crops, are expensive to maintain and can be unwieldy for research purposes. In the 1980s, Brown and colleagues described a need to identify

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Briana L. Gross, Gayle M. Volk, Christopher M. Richards, Philip L. Forsline, Gennaro Fazio, and C. Thomas Chao

methods. The U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) National Plant Germplasm System, Plant Genetic Resources Unit (PGRU) apple collection in Geneva, NY, conserves key genetic resources useful for breeding and research

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R.L. Jarret, G. Lovell, and M. Spinks

The S-9 Plant Germplasm Collection maintains and distributes germplasm of various horticultural crops, including pepper (Capsicum spp.), watermelon (Citrullus lanatus), okra (Abelmoschus spp.), eggplant (Solanum melongena), miscellaneous Solanum spp., sweetpotato (Ipomoea batatas spp.), luffa (Luffa spp.), gourds (Lagenaria and Momordica spp.), squash (Curcurbita moschata), pumpkin (Curcurbita maxima), marigold (Tagetes spp.), Stokes' aster (Stokesia laevis), hibiscus (Hibiscus spp.), Engelman daisy (Engelmannia pinnatifolia), pampasgrass (Cortaderia selloana), ornamental bamboo (Bambusa spp.), and other ornamental grasses. Seed or other propagules of these plant materials are available for research purposes. Detailed information on individual collections and general information on the USDA National Plant Germplasm System will be presented.

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Sandra A. Balch, Cynthia B. McKenney, and Dick L. Auld

Geographically referenced information is an important aspect in the collection of wild plant species. It provides detailed information about the collection site as well as a method of relocating plant populations. In one project, native plants were collected and analyzed for the presence of gamma-linolenic acid, a valuable fatty acid used in medicinal products. In a second project, native wild-flowers were collected and evaluated for potential use as drought-tolerant ornamental landscape plants. All native plants were initially tagged in the spring while in bloom. Each collection site was revisited later for seed collection. Due to a lack of landmarks in the collection area, a GeoExplorer Global Positioning System (GPS) unit was used to capture coordinate data of latitude, longitude, and altitude. This was added to the passport file of each collection site. Differential correction was used to increase accuracy of GPS data to within a range of 10 m. ARC/INFO software was used to assemble, store, and display collection data in map form. This method has been used to document over 300 accessions and identify areas with a high frequency of plants possessing desired characteristics.

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Charles C. Block and Kathleen R. Reitsma

Nine hundred and seventy-seven (977) cucumber (Cucumis sativus L.) accessions from the U.S. National Plant Germplasm System (NPGS) collection were tested for resistance to powdery mildew, caused by the fungus Podosphaera xanthii (Castagne) Braun and Shishkoff, formerly known as Sphaerotheca fuliginea (Schlecht.) Poll. Plants from each accession were evaluated in the greenhouse following inoculation with field isolates of P. xanthii. Each plant was placed into one of three susceptibility classes based on the amount of fungal growth and sporulation on the hypocotyl, stem, petioles and leaves - susceptible (S), intermediate (I) or resistant (R). Of the 977 accessions (9.6%), 94 contained at least one I or R-type plant. Seventeen of the 20 most-resistant accessions came from Asian sources, including China (PIs 418962, 418964, 432860, and 432870), India (PIs 197085, 197088, and 605930), Japan (PIs 279465, 288238, 390258, and 390266), Pakistan (PI 330628), the Philippines (PIs 426169 and 426170), and Taiwan (PIs 321006, 321009, and 321011). A quantitative study was conducted to compare mildew reproduction on S, I, and R-type cucumbers in the greenhouse and under field conditions in Ames, Iowa. Leaf disks were removed weekly and microscopic counts made of spore populations. The leaf disk method was superior to visual rating for ranking and differentiating intermediate from resistant accessions. Both the intermediate (moderately resistant) and highly resistant accessions provided excellent protection against powdery mildew in the field.

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Dennis J. Werner and W.R. Okie

This research was funded in part by the North Carolina Agricultural Research Service (NCARS), Raleigh. The authors wish to thank the following individuals for their interest in the peach PI collection and their contributions to the

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Marivi Colle, Elizabeth N. Straley, Stephanie B. Makela, Sue A. Hammar, and Rebecca Grumet

. In most cases 10 to 15 fruit were tested per plant with a total of 100 to 200 fruit tested for each PI or S 1 family. The PIs retested in the field in 2013 had much lower disease ratings than the full collection of PIs ( t test, P < 0.00001), as

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Joe-Ann McCoy, Mark Widrlechner, and Jeff Carstens

Echinacea is becoming a well-established, high-value crop, both as an ornamental and a dietary supplement. A comprehensive collection of Echinacea germplasm is conserved by the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa, and is available via seed distribution for research and educational purposes (ars-grin.gov/npgs). Representing all nine species collected throughout their respective North American geographic ranges, the Echinacea collection includes 179 accessions. Extensive morphological characterization data associated with this collection have been compiled and are available to researchers on the Germplasm Resources Information Network (GRIN) database to aid in selection criteria. The collection has been used extensively for various research projects, ranging from ornamental breeding studies to HPLC analyses of metabolites of interest to the phytopharmaceutical industry. This poster will summarize the Echinacea collection conserved at the NCRPIS, including a list of available accessions by species, illustrations of seed, and control-pollinated cage propagation methods; and facilities utilized for seed cleaning, testing, and storage. In addition, instructions on how to use the GRIN database to view evaluation data and acquire germplasm will be provided.

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Phillip D. Griffiths, Laura Fredrick Marek, and Larry D. Robertson

characteristic V-shaped lesions originating from the leaf margin, which enlarge causing the plant to wilt and eventually rot. Currently, the most effective approaches to controlling black rot are through good agricultural practices, hot water treatment of seeds

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T. R. Hamilton-Kemp, J. H. Loughrin, and R. A. Andersen

Two methods for collecting headspace vapors produced by plant samples are presented. The first involves entraining volatiles in a stream of air and trapping the entrained compounds on a porous polymer such as Tenax. The volatiles are recovered from the trap by solvent extraction or heat desorption and analysed by gas chromatography. A second method entails removing headspace vapor above plant material with a gas-tight syringe and injecting the sample directly into the gas chromatograph. An evaluation of the usefulness of these techniques will be presented.